AP
The first is the perception that if there's no deal reached, it will be because of Democratic "overreach" that they could have had an agreement this weekend, but that Harry Reid and fellow Senate Democrats killed that agreement, because they wanted more on spending. That might not technically true - Democrats just want to renegotiate the sequester-level spending sooner than Republicans do - but still, the view could emerge of Democrats getting greedy and letting the whole thing go bust.
And the second risk is that if we get to October 17, the world won't actually end right away.
The Treasury might be out of maneuvers, but the Treasury won't literally run out of cash for several more days. Then everyone starts talking about how this was all a phony deadline and deal urgency collapses, and people blame The White House and Treasury for yelling about how the sky is falling.
How the